clearinghouse Tag

Among the proposed BMPs in the Virginia BMP Clearinghouse is Number 4: Soil Compost Amendment. The intent of the measure is to deeply till compacted soils and restore their porosity by amending them with compost. Intuitively, this is a great idea. In my own experience on a small scale, a tilled topsoil layer, rich in organics, can accept a large amount of water. With my rain barrels at home, I can empty 40 gallons of water in 15 minutes into a landscape area less than 9 square feet. Also, I think most of us have seen that construction, particularly in tight sites, essentially destroys the existing soil structure that made it permeable. I think that this measure will see a lot of use when the new regulations go into effect, as it can be credited with as much as a 50% reduction in runoff volume and phosphorus.
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The upcoming regulations will hopefully result in more design flexibility and better stormwater quality. However, for these regulations to work to their fullest extent, localities will need to make changes to development ordinances to fit with the new approach. Here are some examples:
The most cost effective way for developers to reduce runoff volume is to never build pavement. However, the local ordinances often drive the need for pavement through required parking, road width, fire access, road and other factors. There is very good discussion of this in the book Suburban Nation: The Rise of Sprawl and the Decline of the American Dream. A few localities in Virginia have started the process of reducing requirements for pavement in their ordinances, but there is a long way to go.
The new regulations use sheet flow across undeveloped and landscaped areas as a way to reduce runoff volume. It makes a lot of sense...